The present invention relates to an apparatus and method for reducing the deposition of process residues on a surface in a chamber.
In substrate fabrication processes, semiconductor, dielectric, and conductor materials are formed on a substrate and etched to form patterns of gates, vias, contact holes or interconnect lines. These materials are typically formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), oxidation and nitridation processes. For example, in CVD processes, a reactive gas is used to deposit a layer of material on the substrate, and in PVD processes, a target is sputtered to deposit material on the substrate. In oxidation and nitridation processes, a layer of oxide or nitride, typically silicon dioxide or silicon nitride, respectively, is formed by exposing the substrate to a suitable gaseous environment. In etching processes, a patterned etch-resistant mask of photoresist or hard mask is formed on the substrate by photolithographic methods, and the exposed portions of the substrate are etched by an energized gas. In such processes, it is often desirable to change process conditions or stop processing of the substrate at a predetermined stage. For example, in the etching of gate structures, it is desirable to stop etching of overlying polysilicon when the underlying gate oxide is reached. As another example, it is often desirable to stop a deposition, oxidation or nitridation process when a predetermined thickness of material is obtained.
During the substrate fabrication processes, it is desirable to reduce the deposition of process residues on the walls and other surfaces in the chamber. The process residues can flake off and contaminate the substrate. The residues may also interfere with the passage of radiation through the wall, for example, when a widow is provided on the wall and the residues deposited on the window attenuate the intensity of the radiation passing through the window. The radiation may be monitored by conventional process monitoring methods to determine completion of a process stage or reaching of an endpoint of a process. For example, such methods may include, without limitation, (1) plasma emission analysis in which an emission spectra of a plasma in a chamber is analyzed to determine a process endpoint, as disclosed in U.S. Pat. Nos. 4,328,068 and 5,362,256; (2) ellipsometry, in which a polarized light beam reflected from the substrate is analyzed to determine a phase shift and magnitude of the reflected beam, as disclosed in U.S. Pat. Nos. 3,874,797 and 3,824,017; and (3) interferometry, in which radiation reflected off the substrate is monitored as disclosed in U.S. Pat. No. 4,618,262; all of which are incorporated herein by reference in their entireties.
Thus, it is also desirable to reduce the deposition of process residue on the chamber surfaces, especially the surface of a wall or window in the chamber.
The present invention provides an apparatus and method capable of satisfying these needs. In one aspect, the present invention comprises a substrate processing apparatus comprising a process chamber comprising a substrate support, gas inlet, gas energizer, gas exhaust, and a wall having a recess that is sized to reduce the t deposition of process residues therein.
In another aspect, the present invention comprises a substrate processing apparatus comprising a chamber having a support, gas inlet, gas energizer, and exhaust, and a wall, and means for reducing the formation of process residue on the wall, whereby a substrate held on the support may be processed by process gas introduced by the gas inlet, energized by the gas energizer, and exhausted by the exhaust.
In another aspect, the present invention comprises a method of processing a substrate in a chamber, the method comprising placing the substrate in the chamber, providing an energized gas in the chamber to process the substrate, and providing a recess in a wall of the chamber, the recess being adapted to reduce the formation of process residue therein.
In another aspect, a substrate processing apparatus comprising a process chamber comprising a substrate support, gas inlet, gas energizer, gas exhaust, and a wall comprising an internal surface, and a recess originating at the internal surface of the wall, the recess having an aspect ratio sized to reduce the deposition of process residues therein.
In a further aspect, a substrate processing apparatus comprising a process chamber comprising a substrate support, gas inlet, gas energizer, gas exhaust, and a wall having a recess that is sized to reduce the deposition of process residues therein; a magnetic field source adapted to maintain a magnetic field near the portion of the wall having the recess; and a process monitoring system capable of monitoring a process that may be conducted on a substrate in the process chamber through the recess in the wall.
In yet another aspect, a substrate processing apparatus comprising a process chamber comprising a substrate support, gas inlet, gas energizer, gas exhaust, and a wall having a recess that is sized to reduce the deposition of process residues therein; an electrical field source adapted to maintain an electrical field about the recess; and a process monitoring system capable of monitoring a process that may be conducted on in the process chamber through the recess in the wall.
In yet another aspect, a substrate processing apparatus comprising a process chamber comprising a substrate support, a gas inlet, a gas energizer, a gas exhaust, and a sidewall about the support, the sidewall having at least one recess sized to reduce the deposition of process residues therein.
In yet another aspect, the present invention comprises a method of processing a substrate in a chamber, the method comprising placing the substrate in the chamber, providing an energized gas in the chamber to process the substrate, providing a recess in a sidewall of the chamber, and passing radiation through the recess.